Navigation aids are meant to determine speed, direction, orientation, position of a vehicle and these data are used to control and guide the vehicle for safe passage from start to destination. For vehicles moving in fluid medium(s) [air and/or water], the relative speed and direction of the medium in the proximity of the vehicle and effect of movement of medium on the vehicle are also needed to be determined.
For these functions, multiple aids were being used. But rise in traffic density, increase in speed, widening of area of operation, emphasis on economic and fast efficient transit have shifted the focus to new types of Navigation aids which are multifunctional, more accurate and reliable.
At present, such aids can be put under two categories. Satellite based Navigation System GNSS (Global Navigation Satellite System) and INS (Inertial Navigation System). In some systems both the systems are combined to overcome the short comings of both.
GNSS comprising of GPS (USA), GLONASS (RUSSIA) satellites along with augmentation systems DGPS, WAAS (USA), EGNOS (Europe), MTSAT (Japan), GAGAN (India), is being groomed to evolve as primary/sole means of Navigation. Precision (accuracy) of satellite based Navigation is way ahead in comparison to other Radio Navigation Aids and is in the range of 3-30 meters for civilian use. It has the global coverage except in extreme polar-regions. But it has not the other basic performance requirements: Continuity, Availability and Integrity up to the expected level as yet. Satellite based Navigation Systems also suffer from errors that can degrade its precision. The errors are—ionospheric, atmospheric, clock, receiver, ephemeris and position dilution of precision. And of course, the satellite constellation owner country can degrade the precision and even suspend availability of service. Possibilities of black out and jamming are other shortcomings of this type of Navigation aids.
INS is the mainstay of space, marine, submarine and Guided Weapon GN&C (Guidance, Navigation and Control). But it plays supplementary role for commercial vehicle Navigation of other types of vehicles. This is due to (i) high cost of equipment, (ii) mechanical parts hampering reliability in the form of wear, gimbals lock and ring lock (laser) and putting restriction on maneuver, (iii) requirement of position correction by input from other type of Navigation Systems during operation period to overcome integration drift.
Both the systems are unable to determine fluid (air and/or water) movement data in the vicinity of the vehicle through which the vehicle moves and effect of said fluid movement on vehicle movement which is a very important determinant for movement of vehicle through fluid (air and/or water).
The shortcomings of Satellite based Navigation Systems and Inertial Navigation Systems are overcome by method and system of this new invention.